commit 98d9e20b84c31182726ec79a9a7b52c998e60551
author Nicolas Vasilache <nicolas.vasilache@gmail.com> Mon Nov 22 10:22:37 2021 +0000
committer Copybara-Service <copybara-worker@google.com> Mon Nov 22 23:41:51 2021 -0800
tree 01ebb6a3127cc73170192b0f905547604b78531b
parent 866d77ca87ec97fc8cd48add5649427d6c9265ba

[mlir][Vector] Add a vblendps-based impl for transpose8x8 (both intrin and inline_asm)

This revision follows up on the conversation titled:

```[llvm-dev] Understanding and controlling some of the AVX shuffle emission paths```

The revision adds a vblendps-based implementation for transpose8x8 and further distinguishes between and intrinsics and an inline_asm implementation.

This results in roughly 20% fewer cycles as reported by llvm-mca:

After this revision (intrinsic version, resolves to virtually identical assembly as per the llvm-dev discussion, no vblendps instruction is emitted):
```
Iterations:        100
Instructions:      5900
Total Cycles:      2415
Total uOps:        7300

Dispatch Width:    6
uOps Per Cycle:    3.02
IPC:               2.44
Block RThroughput: 24.0

Cycles with backend pressure increase [ 89.90% ]
Throughput Bottlenecks:
  Resource Pressure       [ 89.65% ]
  - SKXPort1  [ 0.04% ]
  - SKXPort2  [ 12.42% ]
  - SKXPort3  [ 12.42% ]
  - SKXPort5  [ 89.52% ]
  Data Dependencies:      [ 37.06% ]
  - Register Dependencies [ 37.06% ]
  - Memory Dependencies   [ 0.00% ]
```

After this revision (inline_asm version, vblendps instructions are indeed emitted):
```
Iterations:        100
Instructions:      6300
Total Cycles:      2015
Total uOps:        7700

Dispatch Width:    6
uOps Per Cycle:    3.82
IPC:               3.13
Block RThroughput: 20.0

Cycles with backend pressure increase [ 83.47% ]
Throughput Bottlenecks:
  Resource Pressure       [ 83.18% ]
  - SKXPort0  [ 14.49% ]
  - SKXPort1  [ 14.54% ]
  - SKXPort2  [ 19.70% ]
  - SKXPort3  [ 19.70% ]
  - SKXPort5  [ 83.03% ]
  - SKXPort6  [ 14.49% ]
  Data Dependencies:      [ 39.75% ]
  - Register Dependencies [ 39.75% ]
  - Memory Dependencies   [ 0.00% ]
```

An accessible copy of the conversation is available [here](https://gist.github.com/nicolasvasilache/68c7f34012584b0e00f335bcb374ede0).

Differential Revision: https://reviews.llvm.org/D114393

GitOrigin-RevId: b2729fda60dbda595e7b5974279d8f860bce75ab